Calculated Key Figure and Formula Variable

Hy experts, i create two calc. key figure, date1 and date2.These calc. key figure use two formula variable to take a value by rep. path from 0FDUEDAY and 0BLINE_DATE .

Then i create another calc. key figure, KF3 and KF4, that doing this operation's:

KF3 : (date1 - date2)* Billing Value

KF4: KF3/ Billing Value

So i have this problem that expose with this example:

Customer | date1 | date 2 | Billling | KF3 | KF4 |

A | 11.06.2009 | 11.06.2009 | 1000 | 0 | 0 |

B | 13.06.2009 | 11.06.2009 | 1000 | 2000 | 2 |

Result | X | X | 2000 | 2000 | X |

The problem is on the KF4's result: is possible to resolve the "X" value?

Thank's a lot.

Sincerely yours.

A. Maraviglia